In fact, there are still many knowledge points about PCB proofing of products in chip processing factories. The following is a brief explanation of some basic knowledge points of PCB proofing, so that everyone can have a further understanding of PCB proofing.

1. Measurement unit of PCB

PCBs are generally measured in imperial rather than metric units, and dielectric thickness, conductor length and width are usually measured in inches or mils. 1mil=0.001in, 1mil=0.0254mm The unit of conductor thickness is ounce (oz, the quality of metal conductor refers to the quality of 1in2 material), commonly used thicknesses are 0.5oz=17.5μm, 1.0oz=35.0μm, 2.0oz=70.0 μm, 3.0oz=105.0μm.

2. The physical characteristics of the transmission line of the PCB circuit board are as follows:

Usually the smt patch factory is doing pcb proofing, and the length L and width W of the transmission line of the smt process workshop equipment are usually set by the PCB layout engineer. The width and spacing of the transmission line are generally not less than 5mil; the thickness H of the transmission line varies due to different manufacturing processes, usually 0.5~3oz.

3. SMT technology equipment oscilloscope

Oscilloscopes are basic tools for high-speed PCB circuit board design and analysis, because high-speed digital signals are square waves that contain high energy and a large number of odd harmonics. Then the fall time decreases and contains more harmonics. The performance of the oscilloscope can affect the analysis of the PCB board. Generally, the bandwidth and sampling frequency of the oscilloscope should be considered. Low-cost, low-performance smt technology equipment oscilloscopes may not be able to display some important information in high-speed PCB design analysis, such as signal interference, undershoot, overshoot, power supply noise, etc.